The development and popularization of mobile networks including Global System of Mobile communication (GSM) etc. in the past 20 years have brought great success to global mobile voice communication services. With the rapid development of personal voice services, wireless data networks have also developed from General Packet Radio Service (GPRS) technology/High Speed Packet Access (HSPA) technology towards Long Term Evolution (LTE) systems, which can provide a high bandwidth wireless access network to better support various mobile applications. However, there are also hidden risks, the most serious of which is resulted from Voice over Internet Protocol (VOIP).
LTE, which is an Internet Protocol (IP) architecture based on an IP Multimedia Subsystem (IMS), is able to realize a voice based on Packet Switching (PS). However, compared with a traditional Circuit Switching (CS) voice service, a voice service based on a PS domain, which has disadvantages including high call drop rate, long call delay, and poor security performance and so on, can hardly achieve the same call service experience as that of the traditional CS voice service. After concerted efforts of the 3rd Generation Partnership Project (3GPP) industry, CS Fall Back (CSFB), i.e., going back to the Second Generation (2G) or the Third Generation (3G) is believed to be an important step to evolve from a CS network to a full IP process. That is, a user resides in an LTE network, when making or answering a voice call, User Experience (UE) access is switched from the LTE network to a 2G/3G network, thereby realizing a voice service in the CS domain of the 2G/3G.
Therefore, traditional CS voice services need to be further developed, because a user still needs to use a traditional CS voice service when making or answering a voice call even in a 4G LTE network. In the meanwhile, with the rapid development of voice services and data services, system capacities of R99 CS voice services need to be improved, or higher data services need to be supported in the condition of the same number of R99 users.
It can be learned according to protocols that settings of a traditional R99 CS 12.2k voice service are as follows: Adaptive Multi-Rate (AMR) coding, 20 ms Transmit Time Interval (TTI), 1/3 convolutional coding and fixed rate-matching. Through simulating based on traditional R99 CS 12.2k voice services, a variety of companies found that a UE can perform decoding successfully without receiving all data of one TTI. FIG. 1 is a schematic diagram showing the accuracy of downlink early stop decoding according to the related art. The horizontal axis in FIG. 1 represents the decoding time (ms) and the vertical axis represents the decoding accuracy. As shown in FIG. 1, data of a 20 ms TTI can be basically decoded successfully within 12 ms to 18 ms, which means that the data after the successfully-decoded data is no longer necessary. In order to reduce such unnecessary power transmission and reduce interference, the industry proposes an early stop decoding mechanism for the R99 service.
The so-called early stop decoding mechanism is explained as follows. For an uplink, a Node B (NodeB) decodes a Dedicated Physical Data Channel (DPDCH) at intervals within each TTI and feeds back a decoding result to a UE. After the decoding succeeds, the UE stops transmission of the DPDCH in the TTI and starts transmission again when the next TTI arrives. For a downlink, the UE decodes a Dedicated Physical Channel (DPCH) at intervals within each TTI and feeds back a decoding result to the NodeB. After the decoding succeeds, the NodeB stops transmission of a DPDCH in the TTI and starts transmission again when the next TTI arrives. After the decoding of the DPDCHs of both the uplink and the downlink succeeds, the UE and the NodeB stop transmission of a Dedicated Physical Control Channel (DPCCH) in the TTI simultaneously and start transmission again when the next TTI arrives. Thus, in order to realize early stop decoding, for the uplink, two conditions must be satisfied: the NodeB should be enabled to acquire a Transport Format Combination Indicator (TFCI) as soon as possible, and the decoding result of the downlink can be fed back to the NodeB to notify the NodeB to stop transmission of the DPDCH in the TTI.
In a traditional R99 service, there are only two channels in the uplink, i.e., a Dedicated Physical Control Channel (DPCCH) and a DPDCH. The DPCCH is used for sending control information including a Pilot, a TFCI and Transmission power Control (TPC) etc. while the DPDCH is used for sending data information, excluding the feedback information about a downlink decoding result. The TFCI includes 10 original bits. After encoding the 10 original bits according to [32,10], the first 30 bits are uniformly distributed in 15 slots of the DPCCH, and a NodeB at least needs 10 ms to obtain a TFCI decoding result. FIG. 2 is a schematic diagram showing the accuracy of uplink early stop decoding according to the related art. The horizontal axis in FIG. 2 represents the decoding time (ms) and the vertical axis represents the decoding accuracy. As shown in FIG. 2, a NodeB may start to try decoding at about 6 ms. It can be seen that the TFCI design in the related art can hardly satisfy requirements of early stop decoding, thus resulting in poor early stop decoding effect of a UE and a NodeB.
At present, there is no effective solution to solve at least one of the problems in the related art that a NodeB side cannot obtain a TFCI in time and a terminal side cannot feed back a downlink decoding result in time during early stop decoding.